An Efficient Solid-Phase Microextraction–Gas Chromatography–Mass Spectrometry Method for the Analysis of Methyl Farnesoate Released in Growth Medium by Daphnia pulex

Methyl farnesoate (MF), a juvenile hormone, can influence phenotypic traits and stimulates male production in daphnids. MF is produced endogenously in response to stressful conditions, but it is not known whether this hormone can also be released into the environment to mediate stress signaling. In the present study, for the first time, a reliable solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS) method was developed and validated for the ultra-trace analysis of MF released in growth medium by Daphnia pulex maintained in presence of crowding w/o MK801, a putative upstream inhibitor of MF endogenous production. Two different clonal lineages, I and S clones, which differ in the sensitivity to the stimuli leading to male production, were also compared. A detection limit of 1.3 ng/L was achieved, along with good precision and trueness, thus enabling the quantitation of MF at ultra-trace level. The achieved results demonstrated the release of MF by both clones at the 20 ng/L level in control conditions, whereas a significant decrease in the presence of crowding was assessed. As expected, a further reduction was obtained in the presence of MK801. These findings strengthen the link between environmental stimuli and the MF signaling pathway. Daphnia pulex, by releasing the juvenile hormone MF in the medium, could regulate population dynamics by means of an autoregulatory feedback loop that controls the intra- and extra-individual-level release of MF produced by endogenous biosynthesis.     

锆基金属有机骨架材料用于四甲基硅烷/异戊烷分离

在半导体工业中,从四甲基硅烷(TMS)/异戊烷混合物中高效捕获异戊烷从而获得超高纯度的TMS是非常重要的。在本工作中,我们选择了具有笼结构的MOF-801,通过其对TMS和异戊烷吸附能力的差异,实现了TMS与异戊烷的分离。气体吸附测试结果表明,在298 K和60 kPa时,MOF-801对异戊烷吸附量为2.56 mmol·g^-1,而其对TMS的吸附量为1.20 mmol·g^-1。理想吸附溶液理论(IAST)计算结果表明,MOF-801对TMS/异戊烷(95∶5,体积比)混合物的分离选择性达到105.8。而之后的液相吸附分离实验进一步验证了MOF-801的分离效果,最终可以得到体积分数大于99.98%的TMS。     

Fabrication of Defect-Engineered MOF-801 Membrane for Efficient Dye Rejection

Although having shown great promise for efficient water treatment, rational structural design and engineering of polycrystalline MOF membranes remain rarely investigated so far. In this study, we prepared well-intergrown MOF-801 membranes with tailorable structural deficiencies in the framework for application in dye rejection. Of particular note, we found that the addition of formic acid as modulator led to the formation of MOF-801 membrane with higher missing-linker number, which was beneficial for increasing water flux with little compromise in dye rejection rate. The MOF-801 membrane prepared in this work exhibited excellent dye rejection performance (CR rejection rate of 99.50 % and water flux of 31.69 L m⁻² h⁻¹ bar⁻¹) as well as excellent long-term stability.     

罗伊氏乳杆菌NCU801对病原菌的粘附抑制性能

采用选择性平板计数法,考察罗伊氏乳杆菌NCU801活菌悬液、死菌悬液以及发酵上清液对大肠杆菌CMCC44496和金黄色葡萄球菌26003粘附Caco-2细胞的影响。结果表明:在竞争试验、排斥试验和置换试验中,罗伊氏乳杆菌NCU801活菌悬液和死菌悬液均能抑制大肠杆菌和金黄色葡萄球菌的粘附;活菌悬液比死菌悬液抑制效果更显著,其中最显著的是活菌悬液对大肠杆菌排斥抑制粘附,粘附抑制率达到(86.8±4.5)%;而发酵上清液在竞争实验中最显著,其次是置换试验,而在排斥实验中对病原菌无影响,说明发酵上清液中的细菌素能够杀死未粘附和已粘附的病原菌。更多还原     

锆基金属有机骨架材料用于四甲基硅烷/异戊烷分离

在半导体工业中，从四甲基硅烷（TMS）/异戊烷混合物中高效捕获异戊烷从而获得超高纯度的TMS是非常重要的。在本工作中，我们选择了具有笼结构的MOF-801，通过其对TMS和异戊烷吸附能力的差异，实现了TMS与异戊烷的分离。气体吸附测试结果表明，在298 K和60 kPa时，MOF-801对异戊烷吸附量为2.56 mmol·g^-1，而其对TMS的吸附量为1.20 mmol·g^-1。理想吸附溶液理论（IAST）计算结果表明，MOF-801对TMS/异戊烷（95∶5，体积比）混合物的分离选择性达到105.8。而之后的液相吸附分离实验进一步验证了MOF-801的分离效果，最终可以得到体积分数大于99.98%的TMS。     

TP—801单板计算机控制凸轮加工

本文介绍了一种用TP—801单板计算机控制的凸轮磨床。分析了加工凸轮的数学原理、控制系统的硬件结构和软件结构。本文还提出了一种控制步进电机按指数规律升降速的方位。本装置已实际使用,有明显的经济效益。     

微机在金属丝拉抻实验中的应用

本文在金属丝拉伸实验中采用TP－801单板机进行设计．精确测量金属丝的杨氏模量，并能确定材料的抗拉强度。